A laser gas purifying system to purify laser gas emitted from a laser apparatus and return purified gas to the laser apparatus may include a first pipe configured to pass the laser gas emitted from the laser apparatus, a purifying apparatus connected to the first pipe and configured to purify the laser gas emitted from the laser apparatus, a second pipe connected to the purifying apparatus and configured to return the purified gas purified by the purifying apparatus to the laser apparatus, and an exhausting device provided in at least one of the first pipe, the purifying apparatus, and the second pipe.